This Phase II project will complete the development of Icon Teacher, a product intended for certain children who require augmentative/alternative communication (AAC) intervention. In AAC systems, children who have not learned to speak may indicate wants and needs by responding nonverbally to symbols that represent desired items or activities (sometimes called "selection-based communication"). Icon Teacher is intended to teach a critical prerequisite for some types of AAC communication - discrimination of icons that are used to represent such items or activities. For present purposes, icons may be defined as physically nonidentical, functionally equivalent stimuli that can serve a representational function within an AAC system. Icon Teacher will be a computer-assisted instructional program to teach equivalence relations between icons and realistic color photographs. The program has three major components: (1) an initial assessment of child readiness for discriminating AAC icons; (2) a programmed instructional sequence for children who do not readily learn the requisite equivalence relations; and (3) a generalization component for skills to a medium selected by the teacher (i.e., handheld device, portable computer screen, or tabletop printed notebook). The instructional component will implement newly developed stimulus control shaping methods that have been shown to teach equivalence relations effectively. When the child completes the Icon Teacher program, s/he will be prepared for the next stage of AAC instruction in which response to the icons is established as an effective method of functional communication. [unreadable] [unreadable]